Part 30 (1/2)

The inferior border of each of these fibro-cartilages is fixed by its anterior part to two osseous proles which terminate the small phalanx behind; these prominences are: _the basilar process_ and _the retrorsal process_ (Fig 96); by its posterior part, this border is continuous with a structure known as _the plantar cushi+on_ (see further on)

The posterior border is directed obliquely upwards and forwards The superior border, which is convex or rectilinear, is thin, and is separated frole Finally, the anterior border, which is directed obliquely doards and backwards, is united to the ligaes in contact

These fibro-cartilages, at their upper extremities, project beyond the hoof, and therefore assist in the forions of the foot,[35] at the part which is called the _crown_ They project less above the hoof in the posterior limbs

[35] Here, for the first time, apropos of the hoof, we use the word 'foot' As in osteology and in y we have, for the sake of clearness of coion limited above by the tarsus, it is necessary to point out here that we eion This we did in conforion of the hoof It is necessary to explain this double employ ascribed to it

[Illustration: FIG 96--THIRD PHALANX OF THE HORSE: LEFT ANTERIOR LIMB, EXTERNAL SURFACE

1, Pyramidal eminence; 2, surface, for articulation with the inferior extremity of the second phalanx; 3, basilar process; 4, retrorsal process]

The posterior and inferior borders of these cartilages inous bulb, constitutes the base of the region, which is commonly called the _heel_--a part of the foot which, as its name implies, is situated posteriorly, but which we ion occupied by the calcaneuy that this latter is situated her up

The _plantar cushi+on_ is a sort of fibrous wedge which occupies the interval bounded by the fibro-cartilaginous plates which we have just been studying Its inferior surface, the form of which we shall find to be reproduced by a portion of the corresponding surface of the hoof, is prolonged anteriorly into a point, while behind it is divided into two branches, which, diverging froes These two branches are separated by a median excavation

The different constituent eleive elasticity to the foot

To finish the examination of the parts contained in the hoof, ill add that a them is also found what is called the fleshy _envelope_, or _flesh_ of the foot

We divide the latter into three regions: the podophyllous tissue, striated or laminated flesh which is spread out over the anterior surface of the third phalanx; the pad, or the hardened skin which corresponds to the upper border of the hoof, and forms a prominence above the podophyllous tissue; and the villous flesh, or velvety tissue which covers the plantar surface of the third phalanx and the plantar cushi+on These three tissues forenic membrane--that is to say, that which produces horny tissue, and consequently regenerates the hoof

It is this latter thatproceed to study

When we examine its anterior surface or the opposite one, the hoof of the horse has the shape of a truncated cone with the base below and the su 97)

Viewed on one of its lateral aspects, it may be compared to a truncated cylinder placed on the surface of the section (Fig 98) We particularly call attention to this latter co a representation of the foot of the horse when viewed laterally

Notwithstanding that the hoof foreneous whole, it consists of three parts, which may be separated from one another by maceration The indication of such disunion, artificially produced, may seem useless It is not so, however, for this division of the hoof will permit us to carry out the study of the latter in a clearer, and consequently a more satisfactory, way The three parts in question are the _wall_, or _crust_, the _sole_, and the _frog_

The _wall_ is that portion of the hoof which we see when the foot rests on the ground It is a plate of horn which, applied to the anterior and lateral surfaces of the foot, diht as it approaches the posterior part of the region Posteriorly and at each side the wall is folded on itself, and is then directed forwards to ter, which ill soon study

[Illustration: FIG 97--LEFT ANTERIOR FOOT OF THE HORSE: ANTERIOR ASPECT

1, Outer side; 2, inner side]

Although the wall forions to which special naiven The anterior part, from the superior border to the inferior, is called the _pince_ or _toe_ for a width of 4 to 5 centimetres External to the toe, and on each side of it, for a distance of 3 or 4 centimetres, is the _nipple_ Behind the _nipples_ are the _quarters_ Still further back, where the wall folds on itself, forion of the _heels_

Finally, the portions of the hich for forward are called the _bars_[36] These are only visible on the inferior surface of the hoof (see Fig 100)

[36] It is to the angle of inflexion or heel that soive the nanate in this fashi+on

The wall, convex transversely, is, in its anterior part (viz, the _toe_) inclined strongly doards and forwards This obliquity tends to becoree that at the quarters it becoround

The internal quarter is less rounded than the external; in addition to this (Fig 97), it approaches more nearly to the vertical direction

[Illustration: FIG 98--LEFT ANTERIOR FOOT OF THE HORSE: EXTERNAL ASPECT

1, Fetlock; 2, spur or beard; 3, pastern; 4, outline deterle; 6, nipple; 7, quarter; 8, heel]